Methods for releasably attaching support members to microfeature workpieces and microfeature assemblies formed using such methods

ABSTRACT

Methods for releasably attaching support members to microfeature workpieces and microfeature assemblies formed using such methods are disclosed herein. A method for processing a microfeature workpiece in accordance with one embodiment includes applying adhesive material to a non-active portion on a first side of a workpiece. The workpiece can include a first active portion and a second active portion separated from each other at least in part by the non-active portion. The method continues by adhesively attaching the first side of the workpiece to a first support member, and releasably attaching the second side of the workpiece to a second support member. The method further includes separating the first active portion from the second active portion while the workpiece is attached to the second support member by cutting through the first support member and the non-active portion of the workpiece. The separation process removes at least approximately all the adhesive material from the non-active portion of the workpiece.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.11/185,045, filed Jul. 19, 2005, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present invention is directed generally toward methods forreleasably attaching support members to microfeature workpieces andmicrofeature assemblies formed using such methods.

BACKGROUND

Existing microelectronic device packages typically include amicroelectronic die attached to a support member, such as a printedcircuit board. Bond pads or other terminals on the die are electricallyconnected to corresponding terminals on the support member, for example,with solder balls or wires. The connection between the die and thesupport member can be protected by encapsulating the die to form adevice package. The package can then be electrically connected to othermicroelectronic devices or circuits in many types of consumer orindustrial electronic products.

Manufacturers are under continuous pressure to reduce the size of theelectronic products they make. Accordingly, microelectronic diemanufacturers seek to reduce the size of the packaged dies incorporatedinto the electronic products. One approach to reducing the size of thepackaged dies is to reduce the thickness of the dies themselves, forexample, by grinding the back side of the wafer from which the die issingulated or diced. One drawback with this approach, however, is thatthin wafers are extremely fragile and therefore difficult to handle.

One approach addressing this drawback is to attach a relatively thickwafer support to the wafer during the grinding process to ensuresurvival of the wafer as well as to facilitate handling of the waferduring processing. One system, for example, includes attaching a waferto a wafer support using an adhesive material. The wafer support is thenremoved after the wafer is processed, for example, by heating the bondbetween the wafer and the wafer support, or by dissolving the bond withan acid. The resulting thin wafer is ready for further processing and/orpackaging.

One drawback with the foregoing approach is that the adhesive materialused to secure the wafer to the wafer support can be difficult to removefrom the wafer after processing. As discussed above, for example,removing the adhesive material may require heat and/or solvents.Accordingly, the wafer can be vulnerable to damage and/or breakageduring removal of the adhesive material. A further drawback of theforegoing approach is that the adhesive material on the wafer maycontact sensitive portions of the individual dies and damage and/orcontaminate the dies. Accordingly, there is a need to improve thehandling of microfeature workpieces during processing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1G illustrate various stages of a method for releasablyattaching a microfeature workpiece to a support member in accordancewith an embodiment of the invention.

FIG. 2 illustrates a stage in a method for releasably attaching amicrofeature workpiece to a support member in accordance with anotherembodiment of the invention.

FIGS. 3A and 3B illustrate stages in a method for releasably attaching amicrofeature workpiece to a support member in accordance with stillanother embodiment of the invention.

DETAILED DESCRIPTION A. Overview/Summary

The present invention is directed toward methods for releasablyattaching support members to microfeature workpieces and microfeatureassemblies formed using such methods. One particular embodiment of sucha method comprises applying adhesive material to a non-active portion ona first side of a workpiece. The workpiece can include a first activeportion and a second active portion separated from each other at leastin part by the non-active portion. The method continues by adhesivelyattaching the first side of the workpiece to a first support member, andreleasably attaching the second side of the workpiece to a secondsupport member. The method further includes separating the first activeportion from the second active portion while the workpiece is attachedto the second support member by cutting through the first support memberand the non-active portion of the workpiece. The separation processremoves at least approximately all the adhesive material from thenon-active portion of the workpiece. In several embodiments, the methodcan further include removing material from the second side of theworkpiece to thin the workpiece after attaching the workpiece to thefirst support member and before attaching the workpiece to the secondsupport member.

Another embodiment of a method for processing microfeature workpiecescomprises applying adhesive material to non-active portions on a firstside of a microfeature workpiece. The workpiece can include a pluralityof microelectronic dies separated from each other at least in part bythe non-active portions. The individual microelectronic dies eachinclude an active portion. The method continues by adhesively attachingthe first side of the microfeature workpiece to a first support member.The method can also include removing material from a second side of theworkpiece to thin the workpiece from a first thickness to a secondthickness less than the first thickness while the workpiece is attachedto the first support member. The method further includes releasablyattaching the second side of the workpiece to a second support memberand, while the workpiece is attached to the second support member,separating each of the plurality of dies from each other. The dies canbe singulated by cutting through the first support member and thenon-active portions of the workpiece to remove at least approximatelyall the adhesive material from the non-active portions of the workpiece.

Additional embodiments of the invention are directed toward microfeatureassemblies. One embodiment of such an assembly includes a microfeatureworkpiece having a first side, a second side opposite the first side, afirst active portion, a second active portion, and a non-active portionseparating the first active portion from the second active portion. Theassembly also includes a sacrificial first support member positionedproximate to the first side of the workpiece. The assembly furtherincludes adhesive material disposed between the workpiece and the firstsupport member. In one aspect of this embodiment, the adhesive materialis disposed on the non-active portion of the workpiece and is at leastgenerally out of contact with the first and second active portions.

The term “microfeature workpiece” is used throughout to includesubstrates upon which and/or in which microelectronic circuits orcomponents, data storage elements or layers, vias or conductive lines,micro-optic features, micromechanical features, and/or microbiologicalfeatures are or can be fabricated using microlithographic techniques.The term “microfeature assembly” is used throughout to include a varietyof articles of manufacture, including, e.g., semiconductor wafers havingactive components, individual integrated circuit dies, packaged dies,and subassemblies comprising two or more microelectronic workpieces orcomponents, e.g., a stacked die package. Many specific details ofcertain embodiments of the invention are set forth in the followingdescription and in FIGS. 1A-3B to provide a thorough understanding ofthese embodiments. A person skilled in the art, however, will understandthat the invention may be practiced without several of these details oradditional details can be added to the invention. Well-known structuresand functions have not been shown or described in detail to avoidunnecessarily obscuring the description of the embodiments of theinvention. Where the context permits, singular or plural terms may alsoinclude the plural or singular term, respectively. Moreover, unless theword “or” is expressly limited to mean only a single item exclusive fromthe other items in reference to a list of two or more items, then theuse of “or” in such a list is to be interpreted as including (a) anysingle item in the list, (b) all of the items in the list, or (c) anycombination of the items in the list. Additionally, the term“comprising” is used throughout to mean including at least the recitedfeature(s) such that any greater number of the same feature and/oradditional types of features are not precluded.

B. Embodiments of Methods for Releasably Attaching Support Members toMicrofeature Workpieces

FIGS. 1A-1G illustrate various stages of a method for releasablyattaching a microfeature workpiece to a support member. Morespecifically, FIGS. 1A-1G illustrate stages of a method for releasablyattaching a front side of the workpiece to a support member using anadhesive disposed only on non-active portions of the workpiece so thatafter processing the support member can be removed from the workpiecewithout contaminating and/or damaging the active portions of theworkpiece.

FIG. 1A is a top plan view of a microfeature workpiece 100 at an initialstage before the workpiece has been attached to a support member. Theworkpiece 100 includes a front side 102 and a back side 104 facingopposite the front side 102. The workpiece 100 further includes aplurality of microelectronic components 106 (e.g., microelectronic dies)having active portions 107 (shown schematically in the Figures)positioned at least proximate to the front side 102 of the workpiece100. The active portions 107 can include circuit elements or devices,such as lines, vias, terminals, transistors, data storage elements,image sensors, or other conductor or semiconductor components arrangedin an array on the workpiece 100. The individual active portions 107 onthe workpiece 100 can be separated from each other by a plurality ofnon-active portions 110. These non-active portions 110 are commonlyaligned with one another to facilitate cutting with a wafer saw,defining so-called streets or scribe lines 111 between the individualcomponents 106. In other embodiments, the active portions 107 and/ornon-active portions 110 can include other features and/or have otherarrangements. For example, in several embodiments the non-activeportions 110 may contain sacrificial active elements (e.g., test ordiagnostic elements) that are active during processing of the workpiece100, but not active when processing of the workpiece is completed.

Referring next to FIG. 1B, an adhesive material 120 is deposited ontoone or more of the non-active portions 110 on the front side 102 of theworkpiece 100. In one aspect of this embodiment, the adhesive material120 can be a bead of adhesive material deposited onto the non-activeportions 110 in a plurality of generally parallel columns 108 and rows109 (corresponding at least in part to the scribe lines 111) that areapproximately as wide as a wafer saw or dicing blade that issubsequently used to singulate the workpiece 100, as discussed ingreater detail below with respect to FIG. 1F.

The adhesive material 120 can include an epoxy material or othersuitable material. As discussed below, the adhesive material 120 doesnot need to have any special release characteristics because all orsubstantially all the adhesive material 120 is removed during thesingulation process. The adhesive material 120 can be deposited onto thefront side 102 of the workpiece using a pen-type dispensing process, ascreen printing process, a photoetch process, precut strips or grids ofadhesive material deposited onto desired portions of the workpiece 100,a tape dispensing process (e.g., a layer of tape over all orsubstantially all the front side 102 of the workpiece 100 with cut-outportions corresponding to one or more of the active portions 106), oranother suitable process known to those of ordinary skill in the art.

FIG. 1C is a side cross-sectional view of the workpiece 100 taken alongline 1C-1C of FIG. 1B after a sacrificial first support member 130(e.g., a carrier substrate) is attached at one or more attachmentlocations 122 on the front side 102 of the workpiece 100 to form amicrofeature assembly 140. Each attachment location 122 can include aportion of adhesive material 120 to secure the first support member 130to the workpiece 100. The first support member 130 can be glass, quartz,or another material that is at least partially transparent. In severalembodiments, for example, the active portions 107 can include imagesensors and the first support member 130 can be at least partiallytransmissive to ultraviolet radiation so that the first support member130 does not obstruct the image sensors during testing (e.g.,illumination of the image sensors). In other embodiments, the firstsupport member 130 can include other suitable materials, includingopaque materials.

The first support member 130 can be sized and shaped to receive theworkpiece 100 and provide support to the workpiece 100 during subsequentprocessing steps. In one embodiment, the first support member 130 can begenerally rigid and has a planform shape at least approximatelyidentical to that of the workpiece 100. In alternative embodiments,however, the first support member 130 can be slightly larger than theworkpiece 100 to avoid the need for precisely aligning the workpiece 100with the first support member 130 when attaching the two together andfor protecting the edge after thinning.

After the first support member 130 has been attached to the workpiece100, the workpiece is ready for additional processing. In oneembodiment, the additional processing can include removing material fromthe back side 104 of the workpiece 100 to reduce its thickness. FIG. 1D,for example, is a side cross-sectional view of the assembly 140 afterthe workpiece 100 has been thinned. More specifically, the workpiece 100has been thinned from a first thickness T₁ (shown in broken lines) to asecond thickness T₂ less than the first thickness T₁. In one embodiment,the material can be removed from the back side 104 by grinding and/oretching. In other embodiments, the material can be removed from the backside 104 in accordance with other existing processes. In any of theseembodiments, the first support member 130 can provide sufficient supportto the workpiece 100 to prevent it from breaking and/or excessivelywarping during processing. In one aspect of these embodiments, thethickness of the assembly 140 after it has been thinned may be slightlygreater than that of a conventional microfeature workpiece, but theoverall size and shape of the assembly 140 can be generally the same asthe size and shape of conventional microfeature workpieces. Accordingly,the equipment and steps used to process the workpiece 100 with the firstsupport member 130 attached can be similar or identical to the equipmentand steps used to process existing microfeature workpieces.

Referring next to FIG. 1E, the assembly 140 can be inverted and attachedas a unit to a second support member 150. In one aspect of thisembodiment, the second support member 150 can include an existing dicingsupport having a frame 152 carrying a replaceable film 153 that caninclude an attachment device 154 (e.g., tape) that releasably adheres tothe back side 104 of the workpiece 100. Accordingly, the second supportmember 150 can support the back side 104 of the workpiece 100, while thefirst support member 130 continues to provide support for the front side102 of the workpiece 100.

Referring next to FIG. 1F, the assembly 140 can be diced, singulated, orotherwise separated to produce a plurality of microelectronic dies 160,including a first die 160 a and a second die 160 b, separated byincisions C. In one embodiment, for example, a wafer saw 170 can be usedto form the incisions C. The saw 170 can cut through the first supportmember 130, the adhesive material 120, the workpiece 100, and in somecases at least a portion of the attachment device 154. The motion of thefirst support member 130 can be controlled during singulation to avoiddamage to the dies 160. In one aspect of this embodiment, the wafer saw170 includes a blade 172 having a width W corresponding at least in partto the width of the non-active portions 110 (FIG. 1B) on the workpiece100. For example, the width W of the blade 172 is at least as wide asthe width of the adhesive material 120 deposited onto the non-activeportion 110 between the first die 160 a and the second die 160 b so thatall or substantially all the adhesive material 120 is removed from theassembly 140 during the singulation process. In other embodiments, thewidth W of the blade 172 may be narrower than the width of the adhesivematerial 120 between the first die 160 a and the second die 160 b, and asuitable post-processing cleaning step can be used to remove theremaining adhesive material 120 from the dies 160.

Referring now to FIG. 1G, a conventional pick-and-place apparatus 180can be used to remove the first die 160 a from the remainder of theassembly 140. In one embodiment, the attachment device 154 remainsattached to the film 153 so that no portion of the attachment device 154is removed with the first die 160 a. In another embodiment, at least aportion of the attachment device 154 can be removed along with the firstdie 160 a, and can later be removed from the first die 160 a in aseparate step. In either embodiment, the first die 160 a can be removedfrom the second support member 150 while the second die 160 b remainsproximate to the second support member 150. The foregoing removalprocess can then be repeated from the second die 160 b and other dies160. In several embodiments, a release agent (e.g., ultravioletradiation) may be used to facilitate removal of the dies 160 from theattachment device 154. After removal, the dies 160 can undergo furtherpackaging and/or processing steps.

One feature of embodiments of the method described above with respect toFIGS. 1A-1G is that the adhesive material 120 is applied to non-activeportions 110 of the workpiece 100. Accordingly, all or at leastapproximately all the adhesive material 120 is removed from theworkpiece 100 during singulation. An advantage of this feature is thatthe adhesive material 120 does not need to have any special releasecharacteristics or require any post-processing cleaning to removeadhesive material residue from the singulated dies. Accordingly, thevarious components of the dies 160 are less likely to be contaminatedand/or damaged as compared to conventional processes that require heat,solvents, and/or post-processing cleaning to remove the adhesivematerial 120 from the workpiece 100.

Another feature of embodiments of the method described above withreference to FIGS. 1A-1G is that the first support member 130 can remainattached to the workpiece 100 as the workpiece is thinned and attachedto the second support member 150. An advantage of this feature is thatthe workpiece 100 can be less likely to be damaged or broken as it istransferred from a grinder or other thickness-reducing tool to thesecond support member 150. The first support member 130 can also providea generally rigid support structure that reduces the likelihood for theworkpiece 100 to bend or warp during additional processing.

Still another feature of embodiments of the method described above isthat the first support member 130 is releasably attached to the frontside 102 of the workpiece 100 over all or substantially all the activeportions 107 of the workpiece 100. An advantage of this feature is thatthe active portions 107 of the workpiece 100 are less likely to bedamaged as the workpiece 100 is processed because the first supportmember 130 provides support and protection. For example, the firstsupport member 130 can shield the active portions 107 from incidentalcontact with surrounding tools, machinery, and/or other components.

C. Additional Embodiments of Methods for Releasably Attaching SupportMembers to Microfeature Workpieces

FIG. 2 illustrates a stage in a method of releasably attaching a supportmember to a microfeature workpiece in accordance with another embodimentof the invention. More specifically, FIG. 2 is a top plan view of theworkpiece 100 after an adhesive material 220 has been deposited onto theworkpiece 100. This stage of this method differs from the stagesdescribed above in that the adhesive material 220 deposited on the frontside 102 of the workpiece 100 is applied in only one direction (as shownby arrows V), as opposed to the bi-directional application of theadhesive material 120 described above with respect to FIG. 1B. Oneadvantage of applying the adhesive material 220 in only one direction isthat the adhesive material 220 is less likely to build up atintersections 112 of the scribe lines 111 on the workpiece 100.Excessive build-up of the adhesive material can result in additionalresidue on the workpiece after singulation that can contaminate theactive portions 107 and/or require additional post-processing removal.In alternative embodiments, the adhesive material 220 may be depositedonto the workpiece 100 in other directions, patterns, and/orarrangements. After applying the adhesive material 220, the workpiece100 can undergo additional processing steps that are at least generallysimilar to those described above with reference to FIGS. 1C-1G.

FIGS. 3A and 3B illustrate stages in a method of releasably attaching asupport member to a microfeature workpiece in accordance with stillanother embodiment of the invention. More particularly, FIG. 3A is a topplan view of the workpiece 100 after a removable cover material 300 hasbeen deposited onto the front side 102 of the workpiece 100 andselectively removed using a masking process or other suitable process,leaving the remaining portions of the cover material 300 only on theactive portions 107. The removable cover material 300 can include aphotoresist or other selectively removable substance. As discussedbelow, the remaining cover material portions 300 can protect the activeportions 107 of the workpiece 100 during subsequent processing steps.

FIG. 3B is a side cross-sectional view of the workpiece 100 taken alongline 3B-3B of FIG. 3A after the first support member 130 is attached tothe workpiece 100 to form the microfeature assembly 140. In one aspectof this embodiment, the cover material portions 300 fill the gapsbetween the first support member 130 and the active portions 106 of theworkpiece 100. One advantage of this arrangement is that the covermaterial 300 can protect the active portions 107 during singulation orsubsequent processing procedures. For example, the cover material 300can protect the active portions 107 from fluids and particulates whiledicing the first support member 130 and the workpiece 100, as describedabove with respect to FIG. 1F. The cover material 300 can be removedfrom the workpiece 100 either during or after the various processingsteps described above.

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from theinvention. For example, anodic bonding or fusion bonding may be used inlieu of or in addition to the adhesive material deposited onto theworkpiece. Aspects of the invention described in the context ofparticular embodiments may be combined or eliminated in otherembodiments. Further, while advantages associated with certainembodiments of the invention have been described in the context of thoseembodiments, other embodiments may also exhibit such advantages, and notall embodiments need necessarily exhibit such advantages to fall withinthe scope of the invention. Accordingly, the invention is not limitedexcept as by the appended claims.

1. A microfeature assembly, comprising: a microfeature workpiece havinga first side, a second side opposite the first side, a firstmicroelectronic die having a first active portion, a secondmicroelectronic die having a second active portion, and a non-activeportion separating the first active portion from the second activeportion; a sacrificial first support member positioned proximate to thefirst side of the workpiece; and adhesive material disposed between theworkpiece and the first support member, the adhesive material beingdisposed on the non-active portion and at least generally out of contactwith the first and second active portions, and wherein all orsubstantially all of the adhesive material is positioned to be removedduring a singulation process.
 2. The microfeature assembly of claim 1,further comprising a second support member positioned proximate to theback side of the workpiece, wherein the workpiece and first supportmember are carried by the second support member.
 3. The microfeatureassembly of claim 2 wherein the second support member includes a dicingframe.
 4. The microfeature assembly of claim 1 wherein the sacrificialfirst support member is at least partially transmissive to ultravioletradiation.
 5. The microfeature assembly of claim 1 wherein thesacrificial first support member includes glass.
 6. The microfeatureassembly of claim 1 wherein the sacrificial first support memberincludes quartz.
 7. The microfeature assembly of claim 1 wherein theadhesive material includes an epoxy material.
 8. The microfeatureassembly of claim 1 wherein the adhesive material includes precut stripsor grids of adhesive material.
 9. The microfeature assembly of claim 1wherein the adhesive material includes tape.
 10. A microfeatureassembly, comprising: a microfeature workpiece having a front side, aback side, and a plurality of microelectronic dies separated from eachother at least in part by a plurality of non-active portions, theindividual dies including an active portion proximate the front side ofthe workpiece; a sacrificial first support member positioned adjacent tothe front side of the workpiece; adhesive material disposed between theworkpiece and the first support member to releasably couple the firstsupport member to the workpiece, the adhesive material being disposed onone or more of the non-active portions of the workpiece and at leastgenerally out of contact with active portions of the individual dies,and wherein all or at least approximately all of the adhesive materialis positioned to be removed during singulation; and a second supportmember positioned adjacent to the back side of the workpiece.
 11. Themicrofeature assembly of claim 10 wherein the second support memberincludes a dicing frame carrying the workpiece and the first supportmember.
 12. The microfeature assembly of claim 10 wherein thesacrificial first support member includes glass.
 13. The microfeatureassembly of claim 10 wherein the sacrificial first support memberincludes quartz.
 14. The microfeature assembly of claim 10 wherein thesacrificial first support member is at least partially transmissive toultraviolet radiation.
 15. The microfeature assembly of claim 10 whereinthe adhesive material includes an epoxy material.
 16. The microfeatureassembly of claim 10 wherein the adhesive material includes precutstrips or grids of adhesive material.
 17. The microfeature assembly ofclaim 10 wherein the adhesive material includes tape.